BMI Calculator for Children
BMI for children and teens aged 2 to 18: enter age, sex, height and weight to see the BMI percentile against WHO reference values and the weight category.
Note: These calculations are for informational purposes only and do not replace professional tax or financial advice. All information without guarantee.
FAQ
Frequently Asked Questions
How is BMI calculated for children?
Children's BMI uses the same formula as adults but is evaluated using age and gender-specific percentile curves. The 90th percentile marks overweight, the 97th marks obesity.
What is a healthy BMI for children?
A healthy BMI for children is between the 10th and 90th percentile for their age and gender. Unlike adults, fixed BMI numbers are not used because healthy ranges change with growth.
Does this calculator replace a doctor visit?
No. This calculator provides general orientation only. For medical questions, or before starting a diet, therapy or treatment, always consult a qualified physician or therapist.
Guide
What is the BMI Calculator for Children?
The BMI calculator for children computes the Body Mass Index and classifies it by age- and sex-specific percentiles.
How does the BMI Calculator for Children work?
Enter the child's age, sex, weight and height. The BMI is computed and compared with Kromeyer-Hauschild reference values. The percentile shows where the child stands relative to their age group.
Key Data and Facts
Underweight: below P10. Normal weight: P10-P90. Overweight: P90-P97. Obese: above P97. Reference values per Kromeyer-Hauschild (2001), standard in Germany.
Step-by-Step Guide
How to calculate your child's BMI step by step: 1. Enter the child's age: the calculator applies to children and adolescents from 2 to 18 years. 2. Select the sex: the reference values differ for boys and girls. 3. Enter the body weight in kg: weigh the child in light clothing. 4. Enter the body height in cm: the child should be measured without shoes. 5. Calculate the BMI: BMI = weight (kg) / (height in m)2. 6. Read off the percentile: the BMI is compared with the reference values according to Kromeyer-Hauschild. Below P3: severe underweight. P3-P10: underweight. P10-P90: normal weight. P90-P97: overweight. Above P97: obesity. 7. Interpret the result: children grow at different rates. A single value is less meaningful than the development over several months. Discuss any abnormalities with the pediatrician.
Calculation Example
Girl, 8 years, 28 kg, 130 cm: BMI = 28 / (1.30)2 = 16.57. This value is roughly at the 50th percentile – normal weight.
Sources
Official sources
Calculations are based on applicable German laws and official data:
Full methodology at Methodology.
Reviewed by Konstantin Iakovlev · Last updated:
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